Codec transformer functions (#176)

* Codec transformer functions

* Just marshalling

Export os.File from world (#175)

Rename World interface to IO (#174)

* Rename World interface to IO

* Rebase and tidy

Flake update (#170)

Expands `os` package and adds CWD root functions (#167)

* os: Add functions to open the current working directory

Introduces `Openwd` and `OpenInwd` to provide convenient access to the current working directory and files within it, abstracting away the explicit `System.Getwd()` call.

* os: Re-export more standard library os package symbols

This change updates the local `os` package to alias a wider range of constants, variables, and functions from the standard library's `os` package, improving the completeness of the local abstraction.

* fmt

* Revert "os: Add functions to open the current working directory"

This reverts commit dbdca34.

os: Introduce a full I/O File interface (#166)

* os: Introduce a full I/O File interface

The `os` package's `Fs` interface methods previously returned `fs.File`,
which is limited to read-only operations. This commit introduces a new
`File` interface that embeds `io.Closer`, `io.ReaderAt`, `io.Writer`,
`io.WriterAt`, and `io.WriterTo`, closely mirroring the capabilities
of `*os.File` from the standard library. `Fs` methods such as `Create`,
`CreateTemp`, `Open`, `OpenFile`, and `OpenInRoot` are updated to
return this more capable `File` type. The existing `os.File` type alias
is renamed to `OsFile` to avoid name collision.

Additionally, the `Env` interface gains an `Expand` method, providing
functionality similar to `os.Expand` for environment variable expansion.
The `.gitignore` file is updated to ignore `.claude/*.local.json` files.

* Potential fix for pull request finding

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Move functional-related code to the fp module (#165)

* Move the fp stuff under fp

* Update `fp` module references and documentation

Reflects the move of functional programming packages into a dedicated `fp` module.
This commit updates all affected import paths in tests and relevant sections
of the `README.md`, along with correcting minor typos in the documentation.

Run on THECLUSTER (#162)

* Run on THECLUSTER

* Nix develop test

* Also setup nix

* Actionlint too

Yet another missing function from the OS interface (#151)

Clean up the codec package and make it generic (#150)

* Clean up the codec package and make it generic

* ope